From document DE 31 04 124 A1 a charge-air cooler for a vehicle with a supercharged internal-combustion engine is known, whereby in order to reduce the size of the charge-air cooler a bypass that has a valve arrangement and that blocks the bypass in a low rpm range of the internal-combustion engine is provided.
Moreover, document DE 31 04 072 C1 describes a process for accelerating the warming-up of an engine in which, depending on the cooling-water temperature and the temperature of the charge air, the charge air is directed to the internal-combustion engine either through a charge-air cooler or through a bypass.
If high charge-air temperatures prevail, however, with the charge-air cooling circuits disclosed in these documents there is the problem that the surface area of the charge-air cooler has to be as large as possible in order to ensure adequate cooling, but it is very difficult to accomplish this because of the cramped conditions that prevail in the engine compartment.
Finally, from document DE 195 47 994 A1 a V-design internal-combustion engine with two exhaust-gas turbo-superchargers that operate in parallel is known, whereby from each of the two exhaust-gas turbo-superchargers a feed line runs to one of two charge-air coolers that are arranged next to each other and whereby from each of the two charge-air coolers a return line runs to an intake system. To create a switchable bypass, provisions are made to ensure that in each case the feed line of the one charge-air cooler is connected to the return line of the other charge-air cooler and that this connection is equipped with a switchable bypass valve.
In all the charge-air cooling circuits described by the above-mentioned documents, there is also the problem that the cooling results that can be achieved are not entirely satisfactory.